[Rakefile] Perform setup on for integration only if needed.

This skips the unneeded update.

Rakefile

@@ -214,8 +214,10 @@ namespace :spec do
     title 'Running the specs'
     sh "bundle exec bacon #{specs('**')}"
 
+    unless Pathname.new('~/.cocoapods/master').exist?
       title 'Ensuring specs repo is up to date'
       sh    "./bin/pod setup"
+    end
 
     title 'Running Integration 2 tests'
     sh "bundle exec bacon spec/integration_2.rb"